Step switcher for regulating transformers



Oct. 24, 1933. B. JANSEN 1,931,869

STEP SWITCHER FOR REGULATING TRANSFORMERS Filed Jan. 13, 1931 4 Sheets-Sheet 1 1933- B. JANSEN 3 ,869

STEP $WITCHER FOR REGULATING TRANSFORMERS Filed Jan. 15, 1931 4 Sheets-Sheet 2 Bernh 0rd Jansen NTOR;

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Oct. 24, 1933. JANSEN 1,931,869

STEP SWITCHER FOR REGULATING TRANSFORMERS Filed Jan. 15, 1951 4 Sheets-Sheet 3 F i 4 L l I I; i I 1 1 2 I I I l a I E1 l r. i D n L C E l C T v I. I

. I B l I I E I i 1/ l 4 I Bunhw N VENT'OR,

-29 ATTQ.

1933- B. JANSEN 3 ,869

STEP SWITCHER FQR REGULATING TRANSFORMERS Fil ed Jan. 13, 1931 4 Sheets-Sheet 4 Bernhard Jansen iNvENToR;

km Attomay Patented Oct. 24, 1933 UNITED STATES s'rnr SWITCHER FOR REGIVILATING TRANSFORMERS Bernhard Jansen, Regensburg, Germany 1 Application January 13, 1931, Serial No. 508,447,

and in Germany January 24, 1930 10 Claims. (01. 171-119! The present invention relates to a switch regulation method by means of which the taps of a transformer can be changed while in normal uninterrupted use.

In a much used form of construction of such step-switches the transformer taps succeeding one another are arranged on a circular contact path and a double-pole switch which can be displaced by a crank is moved from one tap to the next one. The double-pole switch by means of which the changing-over from the tap in use to the tap above orbelow is effected isbesides possessing permanent contacts-generally provided with pre-contacts and bridge-resistances. These establish the connection with the next tap before the preceding one is left.

As with these step-switch regulations the double-pole switch following the contact path moves along the circumference from one tap to the next one, it is necessary that between the taps there should always be, in the direction of the circumference, the gaps neededfor the switchover. In the case of medium or large outputs this requires a great length of the contact path. This circumstance is particularly annoying in the circular arrangement because the surface of the circle increases insquare proportion to the circumference.

It is for this reason that with the step-switches for medium and large outputs which are on the market at the present time the double-pole switch is arranged separately from the step-selector. This, however, necessitates complicated driving mechanisms and the serial connection of several movable contacts, which gives rise to faulty working.

I have now found that it is possible to combine the double-pole switch withthe step-selector,even in the case of medium and large outputs. T0 at-- tain this end the transformer taps are distributed upon the circumference of a circle in such a man ner that from each tap the next tap above orbelow is reached on the chord of a circle of the largest possible length. In the maximum case this chord equals the diameter of the circle. Thus the double-pole switch has now the entire length of the chord of the circle upon which to effect the switch-over, without the circumference having to be unusually large. For this reason also the switch-over proper takes effect in the direction of the chord of the circle. In doing so the doublepole switch which is arranged upon a carriage can move either with the carriage or independently of it. The choice of the switch-over to the next step above or below is efiected' by swinging the carriage with the double-pole switch from one direction of the chord into the other around the tap in use as a centre of rotation. If the chord, as in the maximum case, is the diameter of the'circle, the swinging takes place around the so centre of the circle.

The two fundamental formsof the step-switch regulation are shown in. the drawings in which Fig. 1 is a front elevation of a step-switch arrangement for eight taps, with a tap cut in for 5 normal operation;

Fig. 2 is a plan view of the device of Fig. 1 in the position illustrated in Fig. 1;

Fig. 3 is a front elevation of the device of Fig.

1 showing the device in an intermediate position during the cutting inof another tap;

Fig. 4 shows in plan the position of the device as in Fig. 3;

Fig.5 shows the device of Fig. 1 in front elevation with a different tap cut in;

Fig. 6 illustrates in plan the position of the device as in Fig. 5;

Fig. 'I discloses in front elevation a device similar to that of the foregoing figures but embracing mechanism for effecting a very rapid shifting of the switch from one tap to another;

Fig. 8 is a detail view of said mechanism;

Fig. 9 illustrates in front elevation a modification of the invention showing a tap cut in for normal operation;

Fig. 10 is a plan of the device in the position of Fig. 9; p v

Fig. 11 discloses an elevation of the device of Fig. 9 in an intermediate position it assumes in cutting in a tap;

Fig. 12 is a plan view of the position of the device in Fig. 11; I v

Fig. 13 is an elevation indicating a position of the device of the preceding figures in which two taps are simultaneously cut in;

Fig. 14 shows in elevation a different tap cut Fig. 15 is a plan of Fig. 14, and

Figs. 16 and 17 are respectively an elevation and I plan showing the device in a position in which a still different tap is cut in.

Figs. 1 to '1 represent a step-switch regulation for 8 taps in different working positions. The positions of the device in Figs. 1, 2, 5 and 6 are two permanent positions in which the main A is connected with the transformer-tap 1 or 2, as the case may be. The transformer-taps 1-8 are held together by a supporting bracket R of regular star-octag0n shape. The supporting bracket itself or any other supporting construction which can take its place, is located across the potential of the main A. A crank B is fastened to the driving shait H which shaft passes through the central axis H of said bracket R. Said crank serves to eifect movement of the carriage C to which the double-pole switch D is firmly fastoned. In both ends of the carriage C there are slots T by means of which the carriage canengage the cylindrical holders N of the taps and thus guide itself. With a turn of the crank B the carrtage C therefore describes a shifting movement in the direction of its own longitudinal axis combined with a swinging movement first around the time the crank B is then in its greatest stretching position so that,with the aid of the double-pole switch D, it can exercise a great contact pressure upon the tap cut in. The double-pole switch D has the two-fold function of establishing in the working positions illustrated in Figs. 1, 2 and and 8 respectively a firm connection between the tops 1 and. '2 respectively and the main A, by means of the contacts El and E2 respectively, and of maintaining the connection in the middle or switch-over position of Figs. 3 and 4, after the main contacts E1 and E: have been disconnected from the taps. by way of the resistances G1 and G2, aided by the pre-contacts F1 and Fr.

In the middle or switch-over position the main A. is momentarily connected with both taps l and 2 at the same time, by way of the resistances G1 and G2. Here with a short-circuit current which is reduced to the desired value by the serially connected resistances G1 and G2 flows from the higher tap to the lower one. Nevertheless the doublepole switch must not remain too long in this middie position as. generally speaking, the resistances will not stand along cutting-in time. when, for instance, the double-pole switch D is moved from the middle position into the end position of Figs. 5 and s the pre-contact F1 interrupts the shortcircuit and the main-contact E: soon after bridges over the resistance G: by establishing a direct connection of the tap 2 with the main A.

1h order to spare the resistances G as much as possible the movement of the double-pole switch Dfrom the radial position of Figs. 1 and 2 into the radial position of Figs. 5 and 6 should be effected in as little time as possible. This is achieved by a quick movement of the crank B by virtue of the mechanism, shown in the drawinto in Figs. 7 and 8. As will be seen from said We. the carriage C is locked against rotation meansof a latch M located centrally in the B and projecting when in looking position into an opening M in said carriage. Located on shaft 8, below the crank B, is a. second crank V.

laid crank having at its free end a downwardly projecting pin V. A trip N: for the latch M is pivoted on said crank V. A second shaft H is positioned below shaft 3 and has at its upper end a fitting W provided with three spaced arms Ni, ii: and Ne. The arm N4 has a depending pin N5 acured thereto, said pin being connected by means of a spring J with the depending pin V' a the crank V. The other arms N1 and Nrare provided with upwardly projecting teats.

This mechanism eifects instantaneous movement of the double-pole switch D inthe followin: manner. Upon rotation of the shaft H the spring J is placed under tension but this force is ineffective to move the crank B due to the latch M. However, when the shaft H has been rotated suiliciently to bring the arms Ni or Ni. tinder the trip N3, the teat on said arm strikes the trip N3, releasing the latch M. The force applied to the spring J thereupon acts to effect an instantaneous movement of the carriage C.

In the embodiment of the invention of Figs. 9 to 17 inclusive. the carriage C is also swung from the radial operating position (Figs. 9 and 10) to the chord position (Figs. 11 and 12) by turning the crank B, and the switch D moves with it, but carriage C remains stationary in the chord position while the switch makes an independent movement for establishing contact with the selected tap, i. e. tap 2. For this purpose it is composed of two separate switches K1 and K2, equipped with main contacts E1 and E2 and precontacts F1 and F2 connected by a connector L.

In the working-position shown in Figs. 9 and 10 the connector L and the switch K2 form a stretched angle-lever by means of which the switch K1 is firmly locked. Thus the main A is firmly connected with the tap 1 by way of the main contact El. The counter-position of Figs. 14 and 15 which relates to the tap 2 is reached when the connector L together with the switch Ki hold the switch K2 and its main contact E2 locked. In order to come into the position illustrated in Figs. 14 and 15 from the position illustrated in Figs. 9 and 10 it is, however, necessary to let a shifting force act upon the connector in the direction of the tap 2. This is done by the force-spring J which is stretched by the crank B. There is, however. still a release necessary of the locking of the switch Ki which had been effected by the stretched angle-lever. This is also performed by the crank B which. after complete tension of the spring J strikes against the switch K2 and thereby opens the angle-lever.

Fig. 13 again shows the moment when the main A is connected simultaneously with both taps l and 2 by way of the precontacts F1 and F2 as well as the resistances G1 and (31; only in this form of arrangement the resistances G1 and G2 are not located on the double-pole switch but are in direct connection with each tap. This construction can, however, also be arranged in such a manner that the resistances are permanently connected with the double-pole switch.

The foregoing description shows the process of the switch-over of the main from tap 1 to tap 2 to be as follows:

Starting from the position shown in Figs. 9 and 10, the crank B is rotated to move the carriage C into the position illustrated in Figs. 11 and 12. Leaving the carriage in this position, the crank continues to rotate so as to extend the spring J. A roller on the crank then strikes the switch arm Kz'fiexing the joint between said arm and link L and the extended spring J rocks the switch arms through the position shown in Fig. 13 to that of Figs. 14 and 15. The continued rotation of the crank then swings the carriage into the position shown in Figs. 14 and 15.

If now it is intended to switch over further to tap 3 the carriage C together with the doublepole switch D must be swung into the direction of the chord leading from 2 to 3 until the position of Figs. 16 and 17 is reached. This is eiiected by an additional turn of crank B, the centre of rotation being tap 2 which is in use at the time. Thereupon the crank B through further movement again stretches the spring J and after reaching its end position carries the double-pole switch to tap 3 to effect an instantaneous switching-over. A switching in opposite direction from 3 to 2 to l is attained by simple reversal of the turning movement of crank B.

As has already been stated the uninterrupted switch-over e. g. from tap l to tap 2 is effected by leaving, after release of the main contact E1, the main A connected for an instant with tap 1 by way of the pre-contact F1 and resistance G2. In the middle position this path of the current is replaced by another path of current by way of the pre-contact F2 and the resistance G2 to the tap 2 for so long a time until the main contact E; can take over the direct path of current. The change of the paths of current in the middle position takes place through momentary parallelcircuiting of the second and the subsequent opening of the first path of current. The duration of the parallel circuiting during which a stress is placed upon the resistances G1 and G2 not only by the working current but also by the short-circuit current flowing from the lower to the higher tap, as has already been stated, should be reduced to a minimum. This is done by making the two pre-contacts F1 and F2 dependent each other in their movement by gear-sectors X and X as shown in Figs. 1 to 7 or by a coupling lever as shown in Figs. 9 et seq. The pre-contacts' are equipped with springs Y which cause them to open up as widely as possible. Their opening movement is then limited by one of the two pre-contacts F1 or F2 striking against the corresponding tap l or 2. Through the inter-dependence of the two pre-contacts on another it is only possible in a single position (the middle position shown in Figs. 3, 4 and 13) for the two pre-contacts to touchthe taps at the same time. However, since the middle position of the double-pole switch D is maintained for only a moment, the cutting in time of both resistances G1 and G2 will be equally limited. Practically, therefore, they are stressed only by the working current and not by the short-circuit current that flows between the higher and the lower taps.

The driving of the step-switch regulations can be done by hand or by a motor in such a way that all three phases of a three-phase transformer cut in at the same time or that the phases cut in one after another whereby a triple number of steps is obtained' In general the step-switch regulation is arranged as a separate unit in air or oil outside the transformer. In many cases it can be built (see Fig. 11) directly on to the transformer-duct. The latter is, in that case, preferably constructed as a multiple ductthrough which all transformer taps pass to the step-switch regulation. If it is not desired to lead out all the taps the doublepole switch alone can be arranged outside and the remaining part of the step-switch can be put up inside the transformer. This is possible, as shown in Fig. 13, by providing the carriage with two contacts which are movably connected with the two poles of the double-pole switch that pass through the duct. In this case it is of advantage with the three-phase zero regulation to embrace three step-switches to one whole. The three stepswitches and the three double-pole switches are then put into motion by a single crank shaft which passes through the duct. In this case, which relates to a three-phase transformer with earthed zero-point, the drive by motor can be done from the double-pole switch placed outside. The motor is connected with the zero-point potential and, to prevent excess voltage, is fed by means of an former taps arranged around the circumference of a circle, a movable carriage located between said taps, a double-pole switch connected to the electrical supply of the transformer and operably associated with said carriage and shifting means for moving the switch from a radial position for the normal connection of anyof said taps to the main, to change to the next desired tap, first into registry with the chord between the functioning and selected taps and then into the radial position appropriate to the selected tap.

2. A device as claimed in claim 1 wherein the switch is mounted on said carriage.

3. A step switch device for tapping in a transformer during use comprising a plurality of trans former taps arranged around the circumference of a circle, a movable carriage located between said taps and having slotted ends for engaging said taps, a double-pole switch connected to the electrical supply of the transformer and secured to said carriage, a crank secured to said carriage and means for operating said crank to cause a shifting of said carriage whereby said switch is moved from a radial position for the normal connection of any of said taps to the main, to change to the next desired tap, first into registry with the chord between the functioning and selected taps and then into the radial position appropriate to the selected tap.

4. A step switch device for tapping in a transformer during use comprising a plurality of transformer taps arranged around the circumference of a circle, a movable carriage located between said taps and having slotted ends for engaging said taps, a double-pole switch on said carriage and connected to the source of electrical supply of the transformer, said switch having means for making direct contact with said taps, and having additional means for making momentary contact with said taps during movement of said carriage, a crank secured to said carriage and means for moving said crank to cause a shifting of said switch from a radial position for the normal connection of any of said taps to the main, to change to the next desired tap, first into registry with the chord between the functioning and selected taps and then into the radial position appro priate to the selected tap, momentary contact between the tap cut out by movement of the switch and that cut in by said movement being effected by said additional means.

5. A device as defined in claim 4 wherein the additional means for making momentary contact with the taps during movement of the carriage comprise a plurality of arms pivoted to the switch and having contacts at their upper ends, meshing gear sectors at their lower ends and spring means for expanding the arms to cause the contacts thereon to strike the taps during movement of the switch.

6. A step switch device for tapping in a transformer during use comprising a plurality of transformer taps arranged around the circumference of a circle, a movable carriage located between said taps and having slotted ends for engaging said taps, a double-pole switch connected to the source of supply of said transformer and secured to said carriage, a crank connected to said carriage, means for operating said crank '5 to cause a shifting movement of said carriage whereby said switch is moved from a radial position (or the normal connection of any or said tape to the main, to change to the next desired first into registry with the chord between the functioning and selected taps and then into the radial position appropriate to the selected tap and additional means cooperating with said crank to eflect an instantaneous movement or the carriage.

I. A device as recited in claim 3 wherein means are provided to prevent but a momentary contact between the tap cut out by movement 0! the switch and that cut in by said movement.

8. A step switch device for tannins in a transformer during use comprising a bracket for supporting eight transformer tape around the circumterence of a circle, a shaft journalled centrally in said bracket. a movable carriage located between said taps, said carriage having slotted ends for receiving said taps. a double-pole switch secured to said carriage and connected to the source of supply of said transiormer, a plurality of contacts on said switch for making a direct contact with said taps. a plurality of arcuate arms pivoted at their lower ends to said switch and having pre-contacts at their upper ends, resistance means connecting said switch and said precontacts, spring means for expanding said arcuatc arms, a crank secured to said shaft and to said carriage Ior eflecting a shifting movement of said carriage whereby said switch is moved Irom a radial position for the normal connection of any 0! said taps to the main, to change to the next desired tap, first into registry with the chord between the tunctioning and selected taps and then into the radial position appropriate to the selected tap, said pre-contacts making contact with the tap cut out by movement of said switch and the tap cut in by said movement, and means cooperating with said crank for rendering said last named contact instantaneous.

9. A device as recited in claim 1 wherein the switch is movable independent oi said carriage.

10. A device as recited in claim 1 wherein said switch comprises a pair of levers connected by a link at their upper ends. v

, BERNHARD JANSEN. 

